<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Title</title>
</head>
<body>
	<canvas id="canvas" width="1024" height="768" style="border: 1px solid #aaa; display: block; margin: auto auto">
		<!--兼容降错-->
		当前浏览器不支持 Canvas，请更换浏览器后再试
	</canvas>

	<!--弧-->
	<script>
	window.onload = function () {
		const canvas = document.getElementById('canvas')
		const context = canvas.getContext('2d')

		context.lineWidth = 5
		context.strokeStyle = '#005588'
		context.arc(300, 300, 200, 0, 1.5 + Math.PI)
		context.stroke()
	}
	</script>
</body>
</html>
